Heat exchanger, method of manufacturing the same, and air-conditioning apparatus

ABSTRACT

A heat exchanger includes a first row of flat tubes, a second row of flat tubes, a first header causing first ends of the flat tubes in the first row in a first direction to communicate with each other, a second header causing first ends of the flat tubes in the second row in the first direction to communicate with each other, and a third header that causes the second ends to communicate with each other and connects the first and second rows to cause refrigerant to flow between the first header and the second header. The flat tubes are arranged outside a space between the segments of the third header. A stress-absorbing part is provided in at least a bending target portion of one of the first header and the second header subjected to larger stress from the bending than the other one of the first header and the second header.

TECHNICAL FIELD

The present disclosure relates to a heat exchanger, a method of manufacturing the same, and an air-conditioning apparatus.

BACKGROUND ART

A heat exchanger that is mounted in an indoor unit of an air-conditioning apparatus and operates as a condenser and a heat exchanger that is mounted in an outdoor unit and operates as an evaporator in the air-conditioning apparatus are known. Liquid refrigerant that is condensed in the heat exchanger in the indoor unit is reduced in pressure by an expansion valve and thus turns into a two-phase gas-liquid state, which is a mixture of gas refrigerant and liquid refrigerant. The heat exchanger in the outdoor unit evaporates the liquid refrigerant included in the two-phase gas-liquid refrigerant, so that the two-phase gas-liquid refrigerant turns into low-pressure gas refrigerant. After that, the low-pressure gas refrigerant leaving this heat exchanger enters a compressor mounted in the outdoor unit. The refrigerant is compressed into high-temperature and high-pressure gas refrigerant. Then, the refrigerant is again discharged from the compressor. Such a cycle is repeated.

For the above heat exchangers, heat exchangers including flat tubes that are flat heat transfer tubes each having a flat cross-section have been becoming more popular because of the flat cross-section intended to reduce the resistance of air flow for improvement of energy efficiency and to reduce the volume of each tube for reduction of the amount of refrigerant.

For example, in a heat exchanger including flat tubes, the flat tubes extending vertically and each having a flat cross-section are arranged horizontally side by side such that long sides of the flat cross-sections face each other. The flat tubes each have an upper end and a lower end, which are connected to headers extending horizontally and communicating with the flat tubes. Furthermore, for example, corrugated fins are arranged between the flat tubes arranged horizontally.

In mounting such a heat exchanger including headers arranged vertically in a product, such as an indoor unit and an outdoor unit of an air-conditioning apparatus, the heat exchanger may be bent into, for example, a rectangle, a rectangle with one side open, or an L-shape by using a dedicated bending machine because of constraints due to, for example, the shape or size of the product. In this case, compression or tension in bending the heat exchanger may cause fins located at inner part of a bending target portion of the heat exchanger to be collapsed or cause fins located at outer part of the bending target portion to be separated from the flat tubes, leading to a reduction in heat exchange efficiency.

For related-art techniques, for example, Patent Literature 1 discloses a heat exchanger in which, instead of fins and flat tubes, an air-leakage preventing plate is disposed in a bending target portion. Such a configuration allows the air-leakage preventing plate to be bent in bending the heat exchanger, preventing collapse and separation of fins in the bending target portion and avoiding damage to the fins.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Unexamined Patent Application Publication No. 10-160382

SUMMARY OF INVENTION Technical Problem

Known heat exchangers including headers arranged vertically include a heat exchanger including one upper header corresponding to one row and two lower headers corresponding to two rows. In this heat exchanger, one of the two lower headers is used as an upstream header located on an upstream side in a refrigerant flow direction, and the other one of them is used as a downstream header located on a downstream side in the refrigerant flow direction. The upper header is used as an inter-row header causing the lower upstream and downstream headers to communicate with each other.

In such a heat exchanger, damage to fins, such as collapse and separation of the fins, resulting from bending stress may occur in bending. In addition, an outer header located at outer part of a bending target portion is deformed in bending by a larger amount than an inner header located at inner part of the bending target portion, leading to damage to the outer header. Therefore, the challenge is to establish a structure that avoids damage to the outer header in bending.

For the technique related to the heat exchanger in Patent Literature 1, dividing the headers can avoid damage to the headers. However, the divided headers need to be connected by multiple pipes after bending, and the headers and the pipes need to be brazed. Therefore, this brazing is required in addition to brazing the headers to flat tubes, leading to a complicated operation. The complicated operation results in an increase in number of steps for manufacture of the heat exchanger.

In response to the above issue, it is an object of the present disclosure to provide a heat exchanger that prevents damage to headers and fins in bending without any complicated operation and without an increase in number of steps for manufacture and avoids a reduction in heat exchange efficiency, a method of manufacturing the same, and an air-conditioning apparatus.

Solution to Problem

A heat exchanger according to an embodiment of the present disclosure includes a first row of flat tubes and a second row of flat tubes, each of the fiat tubes extending in a first direction and having a flat cross-section in a second direction orthogonal to the first direction, the flat tubes being spaced apart from each other in the second direction with long sides of the flat cross-sections facing each other, a first header disposed at a first end of each of the flat tubes in the first row in the first direction and causing the first ends to communicate with each other, a second header disposed at a first end of each of the flat tubes in the second row in the first direction and causing the first ends to communicate with each other, and a third header disposed at a second end of each of the flat tubes in the first and second rows in the first direction and located on both the first row and the second row, the third header causing the second ends to communicate with each other and connecting the first and second rows to cause the refrigerant to flow between the first header and the second header. The first row and the second row are arranged side by side. The third header includes segments. The flat tubes are arranged outside a space between the segments of the third header. The first header and the second header are bent by bending. Stress-absorbing part that absorbs stress is provided in at least a bending target portion of one of the first header and the second header that is subjected to larger stress resulting from the bending than the other one of the first header and the second header.

A heat exchanger manufacturing method according to another embodiment of the present disclosure includes assembling components of a heat exchanger into an assembly and brazing the assembly, the components including a first row of flat tubes and a second row of flat tubes, each of the flat tubes extending in a first direction and having a flat cross-section in a second direction orthogonal to the first direction, the flat tubes being spaced apart from each other in the second direction with long sides of the flat cross-sections facing each other, a first header disposed at a first end of each of the flat tubes in the first row in the first direction and causing the first ends to communicate with each other, a second header disposed at a first end of each of the flat tubes in the second row in the first direction and causing the first ends to communicate with each other, and a third header disposed at a second end of each of the flat tubes in the first and second rows in the first direction and located on both the first row and the second row, the third header causing the second ends to communicate with each other and connecting the first and second rows to cause the refrigerant to flow between the first header and the second header, and bending the first header and the second header in the assembly obtained in the assembling. The assembling includes arranging the first row and the second row side by side, dividing the third header into segments, arranging the segments of the third header, arranging the flat tubes outside a space between the segments of the third header, and forming stress-absorbing part that absorbs stress in at least a bending target portion of one of the first header and the second header that is subjected to larger stress resulting from the bending than the other one of the first header and the second header.

An air-conditioning apparatus according to still another embodiment of the present disclosure includes a refrigerant circuit at least including a compressor, a condenser, an expansion valve, and an evaporator. The condenser or the evaporator is the above-described heat exchanger.

Advantageous Effects of Invention

According to an embodiment of the present disclosure, the flat tubes and the third header are not arranged in the bending target portion. In other words, fins, each of which is disposed between the adjacent flat tubes, are also not arranged in the bending target portion. This eliminates the likelihood that damage to the fins, such as collapse and separation of the fins, will occur in bending. The stress-absorbing part that absorbs stress is provided in at least a bending target portion of one of the first header and the second header subjected to larger stress resulting from the bending than the other one of the first header and the second header. Such a configuration prevents damage caused by, for example, interference between the first header and the second header in the bending target portion. Furthermore, the flat tubes and the headers are brazed together, and another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture. This configuration prevents damage to the headers and fins caused by bending, avoiding a reduction in heat exchange efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a refrigerant circuit diagram illustrating an example of an air-conditioning apparatus according to Embodiment 1.

FIG. 2 is a perspective view of an exemplary heat exchanger mounted in the air-conditioning apparatus according to Embodiment 1.

FIG. 3 is a flowchart illustrating steps for manufacture of the heat exchanger of FIG. 2.

FIG. 4 is a perspective view illustrating the heat exchanger of FIG. 2 in a state prior to bending, or pre-bending state.

FIG. 5 is a perspective view of the heat exchanger of FIG. 2 in a state after bending, or post-bending state.

FIG. 6 is a perspective view of a heat exchanger according to Embodiment 2 in the pre-bending state.

FIG. 7 is a perspective view of the heat exchanger according to Embodiment 2 in the post-bending state.

FIG. 8 is a plan view of a heat exchanger according to Embodiment 3 in the pre-bending state.

FIG. 9 is a plan view of a heat exchanger according to Embodiment 4 in the pre-bending state.

FIG. 10 is a perspective view of a heat exchanger according to Embodiment 5 in the pre-bending state.

FIG. 11 is a perspective view of the heat exchanger according to Embodiment 5 in the post-bending state.

FIG. 12 is an enlarged plan view of a bending target portion of the heat exchanger of FIG. 10.

FIG. 13 is a perspective view of a heat exchanger according to Embodiment 6 in the pre-bending state.

FIG. 14 is a perspective view of the heat exchanger according to Embodiment 6 in the post-bending state.

DESCRIPTION OF EMBODIMENTS

Embodiments will be described below with reference to the drawings. Note that components designated by the same reference signs in the figures are the same components or equivalents. This note applies to the entire description herein, Furthermore, note that the forms of components described herein are intended to be illustrative only and the forms of the components are not intended to be limited to those described herein. Additionally, note that the relationship between the sizes of components in the following figures may differ from that between the actual sizes of the components.

Embodiment 1 <Configuration of Air-Conditioning Apparatus 200>

An air-conditioning apparatus according to Embodiment 1 will be described first. FIG. 1 is a refrigerant circuit diagram illustrating an example of an air-conditioning apparatus 200 according to Embodiment 1. In FIG. 1, solid-line outlined arrows represent the flow of refrigerant in a cooling operation, and broken-line outlined arrows represent the flow of the refrigerant in a heating operation.

As illustrated in FIG. 1, the air-conditioning apparatus 200 includes an outdoor unit 201 and an indoor unit 202. The outdoor unit 201 includes a heat exchanger 10, used as an outdoor heat exchanger, an outdoor fan 13, a compressor 14, and a four-way valve 15. The indoor unit 202 includes an indoor heat exchanger 16, an expansion device 17, and an indoor fan (not illustrated). The heat exchanger 10, the compressor 14, the four-way valve 15, the indoor heat exchanger 16, and the expansion device 17 are connected by refrigerant pipes 12, thus forming a refrigerant circuit.

The heat exchanger 10 operates as an evaporator in the heating operation and operates as a condenser in the cooling operation.

The outdoor fan 13 is disposed in proximity to the heat exchanger 10 to provide air, which is a heat exchange fluid, to the heat exchanger 10.

The compressor 14 compresses the refrigerant. The compressed refrigerant is discharged out of the compressor 14 and is then sent to the four-way valve 15. Examples of the compressor 14 include a rotary compressor, a scroll compressor, a screw compressor, and a reciprocating compressor.

The four-way valve 15 switches between a refrigerant flow direction for the heating operation and a refrigerant flow direction for the cooling operation. Specifically, the four-way valve 15 switches between the refrigerant flow directions in the heating operation to connect a discharge port of the compressor 14 to the indoor heat exchanger 16 and connect a suction port of the compressor 14 to the heat exchanger 10. Furthermore, the four-way valve 15 switches between the refrigerant flow directions in the cooling operation to connect the discharge port of the compressor 14 to the heat exchanger 10 and connect the suction port of the compressor 14 to the indoor heat exchanger 16.

The indoor heat exchanger 16 operates as a condenser in the heating operation and operates as an evaporator in the cooling operation. Like the heat exchanger 10, the indoor heat exchanger 16 may be a fin-and-tube heat exchanger. Further examples of the indoor heat exchanger 16 include a microchannel heat exchanger, a shell-and-tube heat exchanger, a heat pipe heat exchanger, a double-pipe heat exchanger, and a plate heat exchanger.

The indoor heat exchanger 16 is also provided with the indoor fan (not illustrated), which provides air, used as a heat exchange fluid, to the indoor heat exchanger 16.

The expansion device 17 expands the refrigerant leaving the heat exchanger 10 or the indoor heat exchanger 16 to reduce the pressure of the refrigerant. The expansion device 17 may be, for example, an electric expansion valve capable of adjusting the flow rate of refrigerant. Usable examples of the expansion device 17 include a mechanical expansion valve including a diaphragm, used as pressure receiving part, and a capillary tube in addition to the electric expansion valve.

<Operations of Air-Conditioning Apparatus 200>

Operations of the air-conditioning apparatus 200 will be described below with the flow of the refrigerant. The cooling operation performed by the air-conditioning apparatus 200 will be described first. The flow of the refrigerant in the cooling operation is represented by the solid-line outlined arrows in FIG. 1. An operation of the air-conditioning apparatus 200 will be described by taking, as an example, a case where air is a heat exchange fluid and the refrigerant is a heat-exchange target fluid.

As illustrated in FIG. 1, driving the compressor 14 causes high-temperature and high-pressure gas refrigerant to be discharged out of the compressor 14. The refrigerant flows as represented by the solid-line outlined arrows. The high-temperature, high-pressure, and single-phase gas refrigerant discharged from the compressor 14 passes through the four-way valve 15 and then enters the heat exchanger 10 operating as a condenser. Once in the heat exchanger 10, the high-temperature and high-pressure gas refrigerant exchanges heat with the air provided by the outdoor fan 13. Thus, the high-temperature and high-pressure gas refrigerant condenses into high-pressure and single-phase liquid refrigerant.

The high-pressure liquid refrigerant leaving the heat exchanger 10 is turned into two-phase refrigerant including low-pressure gas refrigerant and liquid refrigerant by the expansion device 17. The two-phase refrigerant enters the indoor heat exchanger 16 operating as an evaporator. Once in the indoor heat exchanger 16, the two-phase refrigerant exchanges heat with the air provided by the indoor fan (not illustrated). The liquid refrigerant included in the two-phase refrigerant evaporates, so that the refrigerant turns into low-pressure and single-phase gas refrigerant. This heat exchange cools a room. The low-pressure gas refrigerant leaving the indoor heat exchanger 16 passes through the four-way valve 15 and then enters the compressor 14, where the refrigerant is compressed into high-temperature and high-pressure gas refrigerant. The refrigerant is again discharged from the compressor 14. This cycle is repeated.

The heating operation performed by the air-conditioning apparatus 200 will be described below. The flow of the refrigerant in the heating operation is represented by the broken-line outlined arrows in FIG. 1.

As illustrated in FIG. 1, driving the compressor 14 causes high-temperature and high-pressure gas refrigerant to be discharged out of the compressor 14. The refrigerant flows as represented by the broken-line outlined arrows.

The high-temperature, high-pressure, and single-phase gas refrigerant discharged from the compressor 14 passes through the four-way valve 15 and then enters the indoor heat exchanger 16 operating as a condenser. Once in the indoor heat exchanger 16, the high-temperature and high-pressure gas refrigerant exchanges heat with the air provided by the indoor fan (not illustrated). Thus, the high-temperature and high-pressure gas refrigerant condenses into high-pressure and single-phase liquid refrigerant. This heat exchange heats the room.

The high-pressure liquid refrigerant leaving the indoor heat exchanger 16 is turned into two-phase refrigerant including low-pressure gas refrigerant and liquid refrigerant by the expansion device 17. The two-phase refrigerant enters the heat exchanger 10 operating as an evaporator. Once in the heat exchanger 10, the two-phase refrigerant exchanges heat with the air provided by the outdoor fan 13. The liquid refrigerant included in the two-phase refrigerant evaporates, so that the refrigerant turns into low-pressure and single-phase gas refrigerant.

The low-pressure gas refrigerant leaving the heat exchanger 10 passes through the four-way valve 15 and then enters the compressor 14, where the refrigerant is compressed into high-temperature and high-pressure gas refrigerant. The refrigerant is again discharged from the compressor 14. This cycle is repeated.

In the above-described cooling operation and heating operation, liquid refrigerant entering the compressor 14 causes liquid compression, leading to failure of the compressor 14. It is therefore desirable that refrigerant leaving the indoor heat exchanger 16 in the cooling operation or the heat exchanger 10 in the heating operation be single-phase gas refrigerant.

In the evaporator, while the air provided from the fan is exchanging heat with the refrigerant flowing inside heat transfer tubes included in the evaporator, moisture in the air condenses into water droplets on the evaporator. The water droplets, formed on the evaporator, move downward on fins and the heat transfer tubes, fall downward, and are then discharged as drain water under the evaporator.

The heat exchanger 10 operates as an evaporator in the heating operation under low outdoor-air temperature conditions, where moisture in the air may be formed as frost on the heat exchanger 10. For this reason, the air-conditioning apparatus 200 performs a “defrosting operation” to remove frost when the outdoor air is at or below a predetermined temperature (for example, 0 degrees C.).

The term “defrosting operation” as used herein refers to an operation in which hot gas (high-temperature and high-pressure gas refrigerant) is provided from the compressor 14 to the heat exchanger 10 to prevent frost from forming on the heat exchanger 10 operating as an evaporator. The defrosting operation may be performed when the duration of the heating operation reaches a predetermined value (for example, 30 minutes). Furthermore, the defrosting operation may be performed before the heating operation when the heat exchanger 10 is at or below a predetermined temperature (for example, −6 degrees C.). Frost or ice on the heat exchanger 10 is melted by the hot gas provided to the heat exchanger 10 in the defrosting operation.

For example, the discharge port of the compressor 14 may be connected to the heat exchanger 10 by a bypass refrigerant pipe (not illustrated) so that the hot gas from the compressor 14 can be provided directly to the heat exchanger 10 in the defrosting operation. Furthermore, the discharge port of the compressor 14 may be connected to the heat exchanger 10 via a refrigerant flow switching device (for example, the four-way valve 15) so that the hot gas from the compressor 14 can be provided to the heat exchanger 10.

<Heat Exchanger 10>

The heat exchanger 10 mounted in the air-conditioning apparatus 200 according to Embodiment 1 will be described below. FIG. 2 is a perspective view illustrating an example of the heat exchanger 10 mounted in the air-conditioning apparatus 200 according to Embodiment 1. FIG. 3 is a flowchart illustrating steps for manufacture of the heat exchanger 10 of FIG. 2. FIG. 4 is a perspective view of the heat exchanger 10 of FIG. 2 in a pre-bending state. FIG. 5 is a perspective view of the heat exchanger 10 of FIG. 2 in a post-bending state.

In FIG. 2, arrows AF represent an air flow direction in which the air is provided from the outdoor fan 13 (refer to FIG. 1) to the heat exchanger 10, and arrows RF represent a refrigerant flow direction in which the refrigerant provided to the heat exchanger 10 flows in the cooling operation of the air-conditioning apparatus 200. Incidentally, the refrigerant provided to the heat exchanger 10 in the heating operation of the air-conditioning apparatus 200 flows in a direction opposite to that represented by the arrows RF in FIG. 2. For the flat shape in cross-section of each of flat tubes 3 (flat tubes 31 and 32, which will be described later), the dimension in the longitudinal direction of the flat cross-section will be referred to as a width, and the dimension in the lateral direction of the flat cross-section will be referred to as a thickness. In the following description, for example, the longitudinal direction may be referred to as a width direction, and the lateral direction may be referred to as a thickness direction. Furthermore, a direction in which each flat tube 3 extends will be referred to as a first direction X, and the horizontal direction orthogonal to the first direction X will be referred to as a second direction Y. The direction orthogonal to the first direction X and the second direction Y of each flat tube 3, or the longitudinal direction (width direction) of the cross-section of each flat tube 3, is parallel to a flat surface of the flat tube, and will be referred to as a third direction Z. For the sake of convenience, in the following description, the first direction X, the second direction Y, and the third direction Z are the directions in the heat exchanger 10 of FIG. 4 in the pre-bending state. The flat tubes 31 connected to a first header 1 and the flat tubes 32 connected to a second header 2 are collectively referred to as the flat tubes 3. Additionally, although the first direction X, the second direction Y, and the third direction Z are illustrated as being orthogonal to each other in the figures, these directions may intersect each other at angles close to 90 degrees, for example, at 80 degrees.

In Embodiment 1, as illustrated in FIGS. 2 and 5, the heat exchanger 10 is bent in, for example, an L-shape to conform to the shape of a product in which the heat exchanger 10 is to be mounted. The heat exchanger 10 includes the flat tubes 3, which are flat heat transfer tubes, extending in an extension direction, which is the first direction X, and spaced apart from each other in the horizontal direction, which is the second direction Y, orthogonal to the first direction X so that air currents produced by the outdoor fan 13 (refer to FIG. 1) flow through the spaces between the flat tubes. The flat tubes 3 each have a YZ cross-section perpendicular to the first direction X, and the YZ cross-section is flat. Each flat tube 3 has a multi-hole structure including multiple refrigerant passages (not illustrated) through which the refrigerant flows. In particular, in Embodiment 1, the flat tubes 3 are arranged in two rows such that the flat tubes 31 in a first row and the flat tubes 32 in a second row are arranged in the third direction Z orthogonal to the first direction X and the second direction Y.

In addition, corrugated fins 4 are arranged between the flat tubes 31 in the first row and the flat tubes 32 in the second row such that a corrugated fin 4 is interposed between the adjacent fiat tubes 31 in the second direction Y and a corrugated fin 4 is interposed between the adjacent flat tubes 32 in the second direction Y. In other words, the heat exchanger 10 is a fin-and-tube heat exchanger having a two-row structure. A fin 4 is connected between the adjacent flat tubes 31 to transfer heat to the flat tubes 31, and a fin 4 is connected between the adjacent flat tubes 32 to transfer heat to the flat tubes 32. The fins 4 increase the efficiency of heat exchange between the air and the refrigerant. Although the corrugated fins 4 are used in Embodiment 1, plate fins connected to a large number of flat tubes 31 and plate fins connected to a large number of flat tubes 32 may be used. The fins 4 may be omitted because the surfaces of the flat tubes 31 and 32 allow heat exchange between the air and the refrigerant.

Specifically, in the heat exchanger 10, the flat tubes 31 in the first row extend vertically in the first direction X, which is the extension direction, and are spaced apart from each other horizontally, or in the second direction Y. A fin 4 is interposed between the adjacent flat tubes 31. Additionally, in the heat exchanger 10, the flat tubes 32 in the second row extend vertically in the first direction X, which is the extension direction, and are spaced apart from each other horizontally, or in the second direction Y. A fin 4 is interposed between the adjacent flat tubes 32.

The first header 1 is connected to first ends of the flat tubes 31 in the first row in the first direction X, or lower ends of the flat tubes 31 in the first row located on an upstream side in the direction in which air is sent from the outdoor fan 13 (refer to FIG. 1) in the heat exchanger 10. The first header 1 causes the lower ends to communicate with each other. The first header 1 directly receives the lower ends of the flat tubes 31 in the first row located on the upstream side. The first header 1 is connected to the refrigerant circuit of the air-conditioning apparatus 200 by a refrigerant pipe (not illustrated) and causes hot gas refrigerant from the refrigerant circuit to enter the heat exchanger 10. The first header 1 is also called a gas header. The first header 1 causes high-temperature and high-pressure gas refrigerant from the compressor 14 in the cooling operation to enter the heat exchanger 10, and causes gas refrigerant subjected to heat exchange in the heat exchanger 10 in the heating operation to flow out to the refrigerant circuit.

The second header 2 is connected to lower ends of the flat tubes 32 in the second row in the first direction X, and causes the lower ends to communicate with each other. In other words, in the heat exchanger 10, the second header 2 used as a refrigerant distributor is provided at the lower ends of the flat tubes 32 in the second row located on a downstream side in the direction in which the air is sent from the outdoor fan 13 (refer to FIG. 1). The second header 2 directly receives the lower ends of the flat tubes 32 in the second row located on the downstream side. The second header 2 is disposed parallel to the first header 1. The second header 2 is connected to the refrigerant circuit of the air-conditioning apparatus 200 by a refrigerant pipe (not illustrated). When the heat exchanger 10 operates as an evaporator, the refrigerant from the refrigerant circuit enters the second header 2. When the heat exchanger 10 operates as an evaporator, the refrigerant enters the flat tubes 32 in the second row on the downstream side in the heat exchanger 10 through the second header 2, used as a refrigerant distributor, and then flows out of the flat tubes 31 in the first row on the upstream side. The heat exchanger 10 includes the refrigerant passages, through which the refrigerant flows in cross-flow relation to the air.

Second ends of the flat tubes 31 in the first row and second ends of the flat tubes 32 in the second row in the first direction X, or upper ends of the flat tubes, are connected to a third header 5 a and a third header 5 b, which are located on both the first row having the flat tubes 31 and the second row having the flat tubes 32 and cause the upper ends to communicate with each other. The third headers 5 a and 5 b directly receive the upper ends of the flat tubes 31 in the first row and the upper ends of the flat tubes 32 in the second row. The third headers 5 a and 5 b are separate from each other to provide a space in a bending target portion 6 of the heat exchanger 10, and connect the rows to cause the refrigerant to flow between the first header 1 and the second header 2. In other words, only parts of the first and second headers 1 and 2 are arranged in the bending target portion 6 of the heat exchanger 10.

Specifically, in the heat exchanger 10, the first header 1 is located on the upstream side in the refrigerant flow direction RF in the cooling operation of the air-conditioning apparatus 200, and the second header 2 is located on the downstream side in the refrigerant flow direction RF in the cooling operation of the air-conditioning apparatus 200. The third headers 5 a and 5 b are located midway between the first header 1 and the second header 2 in the refrigerant flow direction RF in the cooling operation in the heat exchanger 10. The third headers 5 a and 5 b cause the refrigerant guided from the first header 1 to the flat tubes 31 in the first row and flowing upward through the flat tubes 31 to flow through the flat tubes 32 in the second row to the second header 2. The third headers 5 a and 5 b hold, in the third headers 5 a and 5 b, partitions 7, which are arranged at regular intervals corresponding to the flat tubes 31 and 32 connected to the third headers 5 a and 5 b. Some of the partitions 7 may be omitted. Therefore, the refrigerant provided to the heat exchanger 10 flows through the first header 1 and is then distributed to the flat tubes 31. The distributed streams of refrigerant flow into the flat tubes 31. The refrigerant streams flow upward through the flat tubes 31. At the upper ends of the flat tubes 31, the third headers 5 a and 5 b cause the refrigerant streams to flow to the flat tubes 32. The refrigerant streams enter the flat tubes 32 and flow downward through the flat tubes 32. At the lower ends of the flat tubes 32, the refrigerant streams enter the second header 2 and join together. Then, the refrigerant is discharged through the second header 2.

The above-described heat exchanger 10 is made through the steps for manufacture illustrated in FIG. 3. Specifically, as illustrated in FIGS. 3 and 4, in assembling step S1, a predetermined number of flat tubes 31 and a predetermined number of fins 4 are alternately arranged, and a predetermined number of flat tubes 32 and a predetermined number of fins 4 are alternately arranged. Then, each fin 4 interposed between the adjacent flat tubes 31 and each fin 4 interposed between the adjacent flat tubes 32 are compressed. In such a state, the third headers 5 a and 5 b, which are arranged on opposite sides of the bending target portion 6 of the heat exchanger 10, are attached to the upper ends of the flat tubes 31 and 32 in the first direction X. Furthermore, the first header 1 is attached to the lower ends of the flat tubes 31 and 32 in the first direction X, and the second header 2 is attached to the lower ends of the flat tubes 32 in the first direction X. At this time, the flat tubes 31 and 32 are not arranged in the bending target portion 6 of the heat exchanger 10. The components assembled in the above-described manner are subjected to furnace brazing, thus forming the heat exchanger 10 in the pre-bending state illustrated in FIG. 4. The flat tubes 31 and 32, the fins 4, the first header 1, the second header 2, and the third headers 5 a and 5 b may be assembled in any other order. The order of assembling may be appropriately changed. For example, the flat tubes 31 and 32 may be attached to the first header 1, the second header 2, and the third headers 5 a and 5 b. After that, a fin 4 may be disposed between the adjacent flat tubes 31 and a fin 4 may be disposed between the adjacent flat tubes 32.

Then, in bending step S2, the assembly obtained in assembling step S1, or the heat exchanger 10 in the pre-bending state, is bent in a direction in which the first header 1 is located outward and the second header 2 is located inward by using a jig (not illustrated), for example. Thus, the heat exchanger 10 subjected to bending is obtained as illustrated in FIGS. 2 and 5. In Embodiment 1, the first header 1 is disposed on the upstream side in the air flow direction AF in which the air is provided from the outdoor fan 13 (refer to FIG. 1) to the heat exchanger 10, and the second header 2 is disposed on the downstream side in the air flow direction AF. This arrangement is appropriately changed depending on the positional relationship between the outdoor fan 13 and the heat exchanger 10. Therefore, the first header 1 may be disposed on the downstream side in the air flow direction AF, and the second header 2 may be disposed on the upstream side in the air flow direction AF.

In Embodiment 1, in the bending target portion 6 of the heat exchanger 10, the first header 1 includes stress-absorbing part 1 a to absorb stress that results from bending. Specifically, the stress-absorbing part 1 a is formed by making the first header 1 longer than the second header 2 in the bending target portion 6, and is curved outward away from the second header 2 in a bending direction that is orthogonal to the first direction X. The stress-absorbing part 1 a with such a shape can absorb deformation of the first header 1 in bending.

Advantageous Effects in Embodiment 1

In the heat exchanger 10 in Embodiment 1 and the air-conditioning apparatus 200 including the heat exchanger 10, the stress-absorbing part 1 a of the first header 1 in the bending target portion 6 of the heat exchanger 10 absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In particular, in this heat exchanger 10, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, are brazed together, and another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

In Embodiment 1 described above, the first header 1 includes the stress-absorbing part 1 a. In addition, the bent part 2 a of the second header 2 may also be used as stress-absorbing part.

Embodiment 2

A heat exchanger 10 according to Embodiment 2 of the present disclosure will be described below. FIG. 6 is a perspective view of the heat exchanger 10 according to Embodiment 2 in the pre-bending state. FIG. 7 is a perspective view of the heat exchanger 10 according to Embodiment 2 in the post-bending state.

In Embodiment 2, the first header 1 in Embodiment 1 is partly modified. The heat exchanger 10 and an air-conditioning apparatus 200 in Embodiment 2 have the same configurations as those in Embodiment 1, and explanation of the configurations is omitted. The same components or equivalents are designated by the same reference signs.

For the stress-absorbing part 1 a of the heat exchanger 10 according to Embodiment 2, as illustrated in FIGS. 6 and 7, the stress-absorbing part 1 a of the first header 1 is curved in the first direction X. Specifically, the stress-absorbing part 1 a of the first header 1 in Embodiment 2 is curved toward the third headers 5 a and 5 b, or upward in the first direction X. The stress-absorbing part 1 a with such a shape can absorb deformation of the first header 1 in bending.

Advantageous Effects in Embodiment 2

As described above, in the heat exchanger 10 according to Embodiment 2, the stress-absorbing part 1 a of the first header 1 in the bending target portion 6 (refer to FIG. 4) of the heat exchanger 10 absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with the bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In addition, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6 of the heat exchanger 10. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, are brazed together, and another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

Additionally, the stress-absorbing part 1 a of the first header 1 is curved upward in the first direction X. Such a shape keeps the stress-absorbing part 1 a of the first header 1 from being bent outward in the bending direction. This accordingly makes the configuration more compact than that in Embodiment 1, in which the stress-absorbing part 1 a is curved outward away from the second header 2 in the bending direction.

Embodiment 3

A heat exchanger 10 according to Embodiment 3 of the present disclosure will be described below. FIG. 8 is a plan view of the heat exchanger 10 according to Embodiment 3 in the pre-bending state.

In Embodiment 3, the first header 1 in Embodiment 1 is partly modified. The heat exchanger 10 and an air-conditioning apparatus 200 in Embodiment 3 have the same configurations as those in Embodiment 1, and explanation of the configurations is omitted. The same components or equivalents are designated by the same reference signs.

In Embodiment 3, as illustrated in FIG. 8, the first header 1 of the heat exchanger 10 includes two segments located on opposite sides of the bending target portion 6 (refer to FIG. 4). The stress-absorbing part 1 a is a separate coupling that couples facing ends of the segments of the first header 1, or a first end 1 b and a second end 1 c. In this case, the first and second ends 1 b and 1 c of the first header 1, the stress-absorbing part 1 a, which is the separate coupling, and the other components are assembled together in assembling step S1, and are then brazed at the same time. The stress-absorbing part 1 a has the same shape as that in Embodiment 1 described above, except that the stress-absorbing part 1 a is a separate part. Thus, deformation of the first header 1 can be absorbed in bending.

Advantageous Effects in Embodiment 3

As described above, the heat exchanger 10 according to Embodiment 3 includes the first header 1 including the two segments located on the opposite sides of the bending target portion 6 (refer to FIG. 4) of the heat exchanger 10 and the stress-absorbing part 1 a as a separate part. The stress-absorbing part 1 a absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with the bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In addition, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6 of the heat exchanger 10. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, brazing the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, and brazing the first end 1 b and the second end 1 c of the first header 1 and the stress-absorbing part 1 a as a separate coupling are performed at the same time. Another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

In the example described above, the first header 1 includes the two segments located on the opposite sides of the bending target portion 6 of the heat exchanger 10. The second header 2 may include two segments located on the opposite sides of the bending target portion 6 of the heat exchanger 10. Such a modification also offers the same advantageous effects as those in Embodiment 3.

Embodiment 4

A heat exchanger 10 according to Embodiment 4 of the present disclosure will be described below. FIG. 9 is a plan view of the heat exchanger 10 according to Embodiment 4 in the pre-bending state.

In Embodiment 4, the first header 1 in Embodiment 1 is partly modified. The heat exchanger 10 and an air-conditioning apparatus 200 in Embodiment 4 have the same configurations as those in Embodiment 1, and explanation of the configurations is omitted. The same components or equivalents are designated by the same reference signs.

In Embodiment 4, as illustrated in FIG. 9, the first header 1 of the heat exchanger 10 includes two segments located on opposite sides of the bending target portion 6 (refer to FIG. 4). The stress-absorbing part 1 a is a separate coupling that couples sides of the facing ends of the segments of the first header 1, or the side of the first end 1 b and the side of the second end 1 c. In this case, the sides of the first and second ends 1 b and 1 c of the first header 1, the stress-absorbing part 1 a, which is the separate coupling, and the other components are assembled together in assembling step S1, and are then brazed at the same time. The stress-absorbing part 1 a has a shape similar to that in Embodiment 1 described above, except that the stress-absorbing part 1 a is a separate part. Thus, deformation of the first header 1 can be absorbed in bending.

Advantageous Effects in Embodiment 4

As described above, the heat exchanger 10 according to Embodiment 4 includes the first header 1 including the two segments located on the opposite sides of the bending target portion 6 (refer to FIG. 4) of the heat exchanger 10 and the stress-absorbing part 1 a as a separate part. The stress-absorbing part 1 a absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with the bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In addition, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6 of the heat exchanger 10. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, brazing the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, and brazing the sides of the first and second ends 1 b and 1 c of the first header 1 and the stress-absorbing part 1 a as a separate coupling are performed at the same time. Another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

In the example described above, the first header 1 includes the two segments located on the opposite sides of the bending target portion 6 of the heat exchanger 10. The second header 2 may include two segments located on the opposite sides of the bending target portion 6 of the heat exchanger 10. Such a modification also offers the same advantageous effects as those in Embodiment 4.

Embodiment 5

A heat exchanger 10 according to Embodiment 5 of the present disclosure will be described below. FIG. 10 is a perspective view of the heat exchanger 10 according to Embodiment 5 in the pre-bending state. FIG. 11 is a perspective view of the heat exchanger 10 according to Embodiment 5 in the post-bending state. FIG. 12 is an enlarged plan view of a bending target portion of the heat exchanger 10 of FIG. 10.

In Embodiment 5, the first header 1 in Embodiment 1 is partly modified. The heat exchanger 10 and an air-conditioning apparatus 200 in Embodiment 5 have the same configurations as those in Embodiment 1, and explanation of the configurations is omitted. The same components or equivalents are designated by the same reference signs.

In Embodiment 5, as illustrated in FIGS. 10 and 11, the first header 1 of the heat exchanger 10 is disposed at a lower position in the first direction X than a position of the second header 2. The whole of the first header 1 may be at a lower position in the first direction X than a position of the second header 2. Alternatively, the first header 1 may be at a lower position in the first direction X than a position of the second header 2 only in the bending target portion 6 (refer to FIG. 4). The stress-absorbing part 1 a is disposed at least in the bending target portion 6 (refer to FIG. 4), where the first header 1 is located at a lower position in the first direction X than a position of the second header 2.

As described above, in the heat exchanger 10 according to Embodiment 5, the stress-absorbing part 1 a included in the first header 1 is disposed at a lower position in the first direction X than a position of the second header 2. Therefore, as illustrated in FIG. 12, the stress-absorbing part 1 a of the first header 1 can absorb deformation of the first header 1 without interfering with the bent part 2 a of the second header 2 in bending. In other words, the arrangement positions of the stress-absorbing part 1 a of the first header 1 and the bent part 2 a of the second header 2 are set at vertically different positions such that they do not interfere with each other, thus avoiding interference between the headers in bending. Therefore, the shape of the first header 1 does not need to have any variation, for example, an outward curve in the bending direction or an upward curve. Thus, the heat exchanger 10 according to Embodiment 5 can be made more readily at lower cost than the heat exchanger in Embodiment 1. As the stress-absorbing part 1 a of the first header 1 does not need to be curved outward in the bending direction, the heat exchanger 10 according to Embodiment 5 can accordingly be made more compact than the heat exchanger 10 in Embodiment 1.

Advantageous Effects in Embodiment 5

As described above, in the heat exchanger 10 according to Embodiment 5, the stress-absorbing part 1 a, provided in the bending target portion 6 (refer to FIG. 4) of the heat exchanger 10, of the first header 1 disposed at a lower position in the first direction X than a position of the second header 2 absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with the bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In addition, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6 of the heat exchanger 10. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, are brazed together, and another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

In particular, in this configuration, the first header 1 and the second header 2 are simply arranged at vertically different positions in the first direction X. The shape of the first header 1 does not need to have any variation, for example, an outward curve in the bending direction or an upward curve. Advantageously, the heat exchanger 10 according to Embodiment 5 can be made more readily at lower cost. In addition, as the stress-absorbing part 1 a of the first header 1 does not need to be curved outward in the bending direction, the heat exchanger 10 according to Embodiment 5 can accordingly be made more compact than the heat exchanger 10 in Embodiment 1.

Embodiment 6

A heat exchanger 10 according to Embodiment 6 of the present disclosure will be described below. FIG. 13 is a perspective view of the heat exchanger 10 according to Embodiment 6 in the pre-bending state. FIG. 14 is a perspective view of the heat exchanger 10 according to Embodiment 6 in the post-bending state.

In Embodiment 6, the first header 1 in Embodiment 5, which is a partial modification of the first header 1 in Embodiment 1, is further modified partly. The heat exchanger 10 and an air-conditioning apparatus 200 in Embodiment 6 have the same configurations as those in Embodiment 1, and explanation of the configurations is omitted. The same components or equivalents are designated by the same reference signs.

In Embodiment 6, as illustrated in FIGS. 13 and 14, the first header 1 of the heat exchanger 10 is disposed at a lower position in the first direction X than a position of the second header 2. The whole of the first header 1 may be at a lower position in the first direction X than a position of the second header 2. Alternatively, the first header 1 may be at a lower position in the first direction X than a position of the second header 2 only in the bending target portion 6 (refer to FIG. 4).

Furthermore, in the heat exchanger 10 according to Embodiment 6, the stress-absorbing part 1 a of the first header 1 is longer than part of the second header 2 in the second direction Y in the bending target portion 6 (refer to FIG. 4), and is curved to the second header 2. Such a shape allows the stress-absorbing part 1 a of the first header 1 to absorb deformation of the first header 1 in bending without interfering with the bent part 2 a of the second header 2. In other words, the arrangement positions of the stress-absorbing part 1 a of the first header 1 and the bent part 2 a of the second header 2 are set at vertically different positions such that they do not interfere with each other, thus avoiding interference between the headers in bending. In addition, the stress-absorbing part 1 a is curved to the second header 2. As the stress-absorbing part 1 a of the first header 1 is not curved outward in the bending direction, the heat exchanger 10 according to Embodiment 6 can accordingly be made more compact than the heat exchanger 10 in Embodiment 1.

In the example described above, the first header 1 is disposed at a lower position in the first direction X than a position of the second header 2. The second header 2 may be disposed at a lower position in the first direction X than a position of the first header 1. Furthermore, not only the first header 1 but also the bent part 2 a of the second header 2 may include the stress-absorbing part 1 a. Such a modification also offers the same advantageous effects as those in Embodiment 5.

Advantageous Effects of Embodiment 6

As described above, in the heat exchanger 10 according to Embodiment 6, the first header 1 is disposed at a lower position in the first direction X than a position of the second header 2 and includes the stress-absorbing part 1 a, which is longer than the part of the second header 2 in the second direction Y in the bending target portion 6 (refer to FIG. 4) of the heat exchanger 10 and is curved to the second header 2. The stress-absorbing part 1 a absorbs deformation of the first header 1 in bending. This eliminates the likelihood that the stress-absorbing part 1 a of the first header 1 located outward in bending may interfere with the bent part 2 a of the second header 2 located inward. This prevents damage to the heat exchanger 10 caused by, for example, interference between the first header 1 and the second header 2. In addition, the flat tubes 31 and 32 and the third headers 5 a and 5 b are not arranged in the bending target portion 6 of the heat exchanger 10. This eliminates damage to the fins 4, such as collapse and separation of the fins 4, in bending. Furthermore, the flat tubes 31 and 32 and the headers, or the first header 1, the second header 2, and the third headers 5 a and 5 b, are brazed together, and another brazing does not need to be performed. This eliminates a complicated operation and an increase in number of steps for manufacture.

In this configuration, the stress-absorbing part 1 a of the first header 1 is not curved outward in the bending direction. This configuration can accordingly be made more compact than the configuration of the heat exchanger 10 in Embodiment 1.

REFERENCE SIGNS LIST

1: first header, 1 a: stress-absorbing part, 1 b: end, 1 c: end, 2: second header, 2 a: bent part, 3: flat tube, 4: fin, 5 a: third header, 6: bending target portion, 7: partition, 10: heat exchanger, 12: refrigerant pipe, 13: outdoor fan, 14: compressor, 15: four-way valve, 16: indoor heat exchanger, 17: expansion device, 31: flat tube, 32: flat tube, 200: air-conditioning apparatus, 201: outdoor unit, 202: indoor unit, AF: air flow direction, RF: refrigerant flow direction, X: first direction, Y: second direction, Z: third direction 

1. A heat exchanger comprising: a first row of flat tubes and a second row of flat tubes, each of the flat tubes extending in a first direction and having a flat cross-section in a second direction orthogonal to the first direction, the flat tubes being spaced apart from each other in the second direction with long sides of the flat cross-sections facing each other; a first header disposed at a first end of each of the flat tubes in the first row in the first direction, the first header causing the first ends to communicate with each other; a second header disposed at a first end of each of the flat tubes in the second row in the first direction, the second header causing the first ends to communicate with each other; and a third header disposed at a second end of each of the flat tubes in the first and second rows in the first direction and located on both the first row and the second row, the third header causing the second ends to communicate with each other and connecting the first and second rows to cause the refrigerant to flow between the first header and the second header, the first row and the second row being arranged side by side, the third header including segments, the flat tubes being arranged outside a space between the segments of the third header, the first header and the second header being bent by bending, stress-absorbing part that absorbs stress being provided in at least a bending target portion of one of the first header and the second header that is subjected to larger stress resulting from the bending than an other one of the first header and the second header.
 2. The heat exchanger of claim 1, wherein the first header or the second header subjected to larger stress resulting from the bending is longer than an other one of the first header and the second header in the bending target portion, and the stress-absorbing part is curved in the first direction or a direction orthogonal to the first direction.
 3. The heat exchanger of claim 1, wherein the first header or the second header including the stress-absorbing part is disposed at a lower position in the first direction than a position of an other one of the first header and the second header.
 4. The heat exchanger of claim 1, wherein the stress-absorbing part is provided in one of the first header and the second header that is subjected to the bending in larger part than an other one of the first header and the second header.
 5. The heat exchanger of claim 1, wherein the stress-absorbing part is a separate coupling that couples facing ends of the first header or the second header.
 6. The heat exchanger of claim 1, wherein the stress-absorbing part is a separate coupling that couples sides of facing ends of the first header or the second header.
 7. The heat exchanger of claim 1, further comprising fins, each of the fins being interposed between the flat tubes that are adjacent in the second direction.
 8. A heat exchanger manufacturing method comprising: assembling components of a heat exchanger into an assembly and brazing the assembly, the components including a first row of flat tubes and a second row of flat tubes, each of the flat tubes extending in a first direction and having a flat cross-section in a second direction orthogonal to the first direction, the flat tubes being spaced apart from each other in the second direction with long sides of the flat cross-sections facing each other, a first header disposed at a first end of each of the flat tubes in the first row in the first direction, the first header causing the first ends to communicate with each other, a second header disposed at a first end of each of the flat tubes in the second row in the first direction, the second header causing the first ends to communicate with each other, and a third header disposed at a second end of each of the flat tubes in the first and second rows in the first direction and located on both the first row and the second row, the third header causing the second ends to communicate with each other and connecting the first and second rows to cause the refrigerant to flow between the first header and the second header; and bending the first header and the second header in the assembly obtained in the assembling, the assembling including arranging the first row and the second row side by side, dividing the third header into segments, arranging the segments of the third header, arranging the flat tubes outside a space between the segments of the third header, and forming stress-absorbing part that absorbs stress in at least a bending target portion of one of the first header and the second header that is subjected to larger stress resulting from the bending than an other one of the first header and the second header.
 9. The heat exchanger manufacturing method of claim 8, wherein the assembling includes making the first header or the second header subjected to larger stress resulting from the bending longer than an other one of the first header and the second header in the bending target portion, and curving the stress-absorbing part in the first direction or a direction orthogonal to the first direction.
 10. An air-conditioning apparatus comprising a refrigerant circuit at least including a compressor, a condenser, an expansion valve, and an evaporator, wherein the condenser or the evaporator is the heat exchanger of claim
 1. 